This invention is concerned with certain heterocyclic carbon compounds having one hetero-N-atom. More particularly, it relates to 3(2H)-isoquinolones and 3-alkoxyisoquinolines which have hypotensive and peripheral vasodilating properties. Although the compounds of the present invention are of the same basic ring system as the isoquinoline, 6,7-dimethoxy-1-veratryl-3-isoquinolinol described by G. N. Dorofeenko and V. G. Korobkova, J. Gen. Chem., USSR., 40, 230 (1970), they differ substantially in biological activity. Thus, for example, the compounds of the present invention are active orally as hypotensive and peripheral vasodilating agents whereas the prior art isoquinolinol is essentially inactive.